Manufacture of tiles

ABSTRACT

Apparatus for cutting a continuously moving ribbon of tile forming material into discrete tiles of equal length and subsequently trimming the leading edge of each tile, comprises means for moving the ribbon past a cutting station and then a trimming station. At at least one of said stations there is provided a knife mounted on a knife holder reciprocable longitudinally of the direction of travel of the ribbon or tiles. The means for reciprocating the knife holder include a crank member adapted to be rotated once for each length of tile that passes said one station, the throw of the crank member being selected so that during the cutting action of the knife the forward linear speed of the knife is first less than, then greater than, and then finally less than the speed of the ribbon or tile being cut.

United States Patent [1 1 Matthews [451 Dec.4, 1973 MANUFACTURE OF TILES [75] Inventor: Douglas Frederick Matthews,

Reigate, England [73] Assignee: Redland Tiles Limited, Reegate,

England 22 Filed: Oct. 2, 1972 21 Appl No.: 293,949

[30] Foreign Application Priority Data Oct. 25, 1971 Great Britain 49,541/71 [52] US. Cl 83/110, 83/300, 83/318, 83/404 [51] Int. Cl. 823d 25/04 [58] Field of Search 83/110, 300, 303, 83/318-320, 404

[56] References Cited UNITED STATES PATENTS 2,228,162 1/1941 Benham et a1 83/303 X Primary ExaminerJ. M. Meister Attorneylrvin S. Thompson et al.

[5 7 ABSTRACT Apparatus for cutting a continuously moving ribbon of tile forming material into discrete tiles of equal length and subsequently trimming the leading edge of each tile, comprises means'for moving the ribbon past a cutting station and then a trimming station. At at least one of said stations there is provided a knife mounted on a knife holder reciprocable longitudinally of therdirection of travel of the ribbon or tiles. The means for a reciprocating the knife holder include a crank mem ber adapted to be rotated once for each length of tile that passes said one station, the throw of the crank member being selected so that during the cutting action of the knife the forward linear speed of the knife is first less than, then greater than, and then finally less than the speed of'the' ribbon o'r-til'erbeing cut.

10 Claims, 4 Drawing Figures MANUFACTURE or TILES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to cutting apparatus, and more particularly to apparatus for dividing a continuously moving ribbon of tile forming material deposited on pallets, into discrete lengths.

2. Prior Art One known form of such apparatus has a conveyor for continuously moving a ribbon of material past a cutting station, the ribbon being supported on a stream of individual pallets. At the cutting station a knife holder ismounted for reciprocal motion longitudinally of the direction of travel of the ribbon by a pneumatic cylinder acting against a spring. Mounted on the knife holder is a knife operated by another pneumatic cylinder to move towards-and away from the ribbon to cut the ribbon. Such a machine may be usefully employed at low speeds of tile making e.g., at a speed of 70 tiles/- minute. However, it has been found that if the tile making speed is increased to, say 100 tiles/minute or more, the inertia forces at the ends of the reciprocating stroke of the knife holder cause an unsteady linear movement of the knife holder which adversely affects the quality of the succeeding cut by the knife.

Various attempts have been made to overcome this problem but no solution has been found up to now which is satisfactory at higher speeds.

In one proposed solution the knife holder was mounted on an endless loop drive means extending longitudinally of the conveyor, the knife performing its cutting action during the passage of the knife holder along the lower pass of the loop. However, in practice, it was found difficult to obtain sufficient synchronism of speed between the ribbon carrying conveyor and the knife holder.

In another proposed apparatus a knife holder was reciprocated by a crank, the speed of the knife holder being synchronised to the speed of the ribbon to be cut. However, in order to obtain synchronism for a sufficient time the throw of the crank was made twice that of the length of the tiles to be cut and the knife holder was provided with two knives in sequence, each knife being used for cutting alternate tiles.

However, when it is necessary to trim the front edge of each tile it is essential that a part of the length of the tile should drop down between a first conveyor moving at one speed and a second conveyor moving at a faster speed so that during subsequent curing of the tiles whilst in line, the adjacent ends of the tiles do not rejoin into a continuous ribbon. Such operation is not possible using the apparatus described above employing two knives which serve to cut alternate tiles. Moreover if one were to employ a cutting knife and a trimming knife the crank speed would have to be increased and at higher speeds the dwell of the crank would not allow the knife to perform its cutting operation without deforming the tiles.

SUMMARY THE INVENTION According to the invention there is provided apparatus for cutting a continuously moving ribbon of tile forming material into discrete tiles of equal length and subsequently trimming the leading edge of each tile, comprising means for moving the ribbon past a cutting station at which the ribbon is cut into individual tiles and then past a trimming station at which the leading edge of each tile is trimmed, therebeing-provided at at least one of said stations a knife holder mounted for reciprocal movement longitudinally of the direction of travel of the ribbon or tiles, means to effect said reciprocal movement of the holder, a knife mounted on the holder, and means to move the knife relative to the holder to perform its cutting action, said means for reciprocating the holder including a crank member, characterised in that the crank member is adapted to be rotated once for each length of tile that passes said one station and the throw of the crank member is selected so that during the, cutting action of the knife the forward linear speed of the knife is first less than, then greater than, and then finally less than the speed of the ribbon or tile being cut.

Preferably'the circumference of the circle described by the crank member is between 1 percent and 3 percent, for example 2 percent, greater than each said tile length.

It is also preferred that the crank member is linked to the knife holder by a connecting rod, the axis of reciprocation of that end of the connecting rod attached to the holder being tangential to the circle of motion of the crank member.

There is preferably provided a first conveyor for moving the ribbon to be cut to the cutting station and the tiles to be trimmed to the trimming station, and a second conveyor for moving the individual tiles from the trimming station, thespeed of the second conveyor being greater than that of the first conveyor so that the material removed from each tile when it is trimmed does not lodge on the preceding tile.

BRIEF DESCRIPTION OF THE'DRAWINGS FIG. 1 is a side view of part of a tile manufacturing apparatus by way of example incorporating the invention,

FIG. 2 is a diagram showing the relative motion of the ribbon and the knife holder.

FIG. 3 is a diagrammatic representation of the'drive to the various parts of the apparatus, and

FIG. 4 is a detailed view showing the method of adjustment of part of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a tile extrusion apparatus comprises a first conveyor 11 which carries a stream of closely spaced pallets 12 under a concrete depositing apparatus 13 including a hopper and shaping rollers where concrete is extruded as a continuous ribbon 8 on the pallets and shaped in transverse cross-section to the profile of a tile. The conveyor 11 then carries the pallets and the freshly formed ribbon of concrete under a knife unit 14 which first cuts the ribbon transversely into individual tile forming lengths 9 and then, as a separate operation, trims the leading edge of each tile, the knife unit performing said cutting and trimming operations at positions corresponding to the ends of the pallets 12. The construction of the conveyor 11 is of no importance to this invention but, in this embodiment, is substantially of the kind described in the specification of our British'Pat. No. 1,242,441 and comprises an endless loop of links 15, on which the pallets 12 are supported, passing around a sprocket wheel 16 and a guide wheel 17. The sprocket 16 is driven so that the pallets move through the apparatus continuously in an endless head to tail stream. In this embodiment the pallets move at a constant speed but this is not essential. Belt conveyors l8 and 19 respectively supply empty pallets and take away the pallets bearing the freshly formed tiles 10. The takeaway conveyor 19 is driven at a speed higher than that of the links 15, for reasons hereafter discussed.

The knife unit 14 comprises a reciprocating carriage 21 supported on two cross head slides 22 extending above and longitudinally of the line of travel of the pallets 12 and the ribbon thereon. Mounted at one end of the carriage 21 is a cutting knife assembly 23, and a trimming knife assembly 24 is mounted at the other end of the carriage. Each knife assembly 23, 24 comprises a knife 25, 26 attached to the piston 27 28 of a pneumatic cylinder 29, 30 by means of which the knives may be moved towards and away from the concrete and pallets. The knives 25, 26 are guided for movement parallel to guide surfaces 31, 32, the cutting knife 25 being normal to the concrete ribbon and the trimming knife being inclined rearwardly relative to the concrete. The trimming knife assembly 24 is mounted on a sub-frame 35 which is movable relative to the reciprocating carriage 21 longitudinally of the line of travel of the pallets, whereby the spacing between the two knife assemblies may be varied so that the knives 25, 26 are spaced apart by slightly less than an integral number of divided tile lengths (in this embodiment two lengths). The method of effecting such adjustment is shown in FIG. 4, and comprises two studs 37 and 38 fixed to the carriage 21 and two nuts 39 and 40, each nut having a tapered portion 41, 42, on those studs. The studs 37 and 38 project through a hole 43 in the sub-frame 35 and the sides of the hole 43 are tapered to correspond to the angle of taper of the nuts 39 and 40. To move the sub-frame 35 to, say, the left as seen in FIG. 4, it is merely necessary to slacken off the right hand nut 40 and thereafter to tighten up the left hand nut 39 so that the engagement of the tapered portion 41 with the hole 43 moves the sub-frame 35 across until it once again engages the tapered portion 42.

The carriage 21 is caused to reciprocate on the slides 22 by a rotating crank member 45 and a connecting rod 46. In this embodiment the crank member 45 comprises a disc-like member mounted on a shaft 47 (FIG. 3) and has a hole 48 adjacent its periphery for attachment of one end of the connecting rod 46. The shaft 47 is driven at a speed proportional to the speed of the conveyor 11, such that the crank member makes one rotation and the carriage 21 reciprocates once, for each pallet 12 that passes the knife unit 14. This desired speed relationship between the crank member 45 and the conveyor 1 1 is achieved by a gear train shown in FIG. 3 which includes a sprocket 51 mounted on the same shaft as the sprocket wheel 16. The sprocket 51 drives an idler sprocket 52 by a chain 53. Mounted for rotation with the sprocket 52 is a further sprocket 52a and a chain 54 passes around the sprocket 52a and also further sprockets 55, 56, 57, 58 and 59. The shaft 47 of the crank member 45 carries a sprocket 61 which is connected by a chain 62 to a sprocket 57a mounted for rotation with the sprocket 57. Thus, the shaft 47 is rotated by a drive from sprocket 51 through chain 53 to sprocket 52, thence from sprocket 520 by chain 54 to the sprocket 57, and finally from sprocket 57a by chain 62 to the sprocket 61. The relative sizes of the sprockets 51 and 61 determine the speed relationship between the crank member 45 and the conveyor 1 1. Adjustment of the relative positions of the pallets 12 and the crank member 45, and thereby the phase relationship between the pallets and the knife assembly 23 on the reciprocating carriage 21, may be necessary, and to effect such adjustment the arrangement of sprockets 55, 56, 57, 58 and 59 are used. Sprockets 56 and 59 are the same size as each other and are inter-connected by a frame which is slidable in a direction parallel to the line adjoining the centres of those sprockets. The other sprockets are also so positioned that the lengths of the chain 54 running between adjacent sprockets are all parallel to the line joining the centres of the sprockets 56 and 59. Thus during adjustment of the frame 70 any decrease in the length of chain between, say, sprockets 55 and 57 is exactly matched by an increase in the length of chain between sprockets 58 and 52a, so that no slackness or overstretching of the chain will occur. Movement of the frame 70 is effected by a screw and nut device (not shown) which is operated by a hand wheel 63 on the knife unit 14 (see FIG. 1).

The knife assemblies 23 and 24 are pneumatically operated as mentioned above, and are controlled by a servo system. The control circuit is in turn operated by an electrical system including a microswitch having an operating arm engaged by a cam rotating at the same speed as the crank member shaft 47. The cam is mounted on a shaft carrying a sprocket 64 (see FIG. 3) driven by a chain 65 from a sprocket 66 mounted to rotate with the sprocket 57. Means are provided for varying the relative positions of the cam and the arm operating the microswitch whereby both the position in the reciprocal movement of the carriage 21 at which downward motion of the knives is initiated may be varied, and also the length of time for which the knives are moved downwardly may be varied. Such adjustment is necessary because there is a constant delay in the pneumatic circuits irrespective of the speed at which the conveyor 11 is operating, and therefore the higher the speed of the conveyor 11 the earlier it is necessary to initiate motion of the knives if they are to cut the ribbon at the correct point in the cycle.

It will be obvious that the carriage 21 does not move at a constant speed during the reciprocating movement. It is thus necessary to select the radius of the crank member 45 and to adjust the other design details, dependent on the speed of the conveyor 11, such that the carriage and the conveyor are synchronized sufficiently during the period of the cut. In this embodiment the linear speed of the conveyor is selected to be equivalent to tiles/minute. At this speed, it has been found that it is possible, in the manner now to be described, to maintain the forward linear speed of the knives substantially constant and equal to the linear speed of the conveyor for a distance of up to two inches of travel of the conveyor. During this period of time the knives perform their respective cutting and trimming operations and, because of the substantially equal linear speeds of the conveyor and the knives, the knives do not destroy the shape of the tiles.

More particularly, the line of travel of the point at which the connecting rod 46 is connected to the carriage 21 is arranged to be tangential to the circle of motion of the crank member 45. If the radius of the crank member is then selected such that the circumference of its path of travel is exactly the same length as one tile,

then the circumferential speed of the crank member will be the same as the linear speed of the conveyor, and the linear speed of the carriage 21 and of the conveyor will therefore be matched instantaneously once each cycle. However, it will be clear that both before and after the top-dead-centre position of the crank at which such synchronism occurs, the knife will be moving slower than the pallets, as the top-dead-centre position is the point of fastest motion. Thus, in accordance with this invention, a slightly increased radius of the crank member 45 is selected whereby the circumference of the crank member is slightly greater than the length of one tile. Hence the speed of the carriage will increase from a speed which is at first slower than the conveyor speed to a speed which at top-dead-centre is slightly faster than the conveyor speed and then decreases again to a speed slower than the conveyor speed. Preferably the circumference of the crank member is increased so that it is between 1 percent and 3 percent greater than the length of each tile. In one particular example, each pallet has a length of 420.34mm., and the corresponding radius of the crank to produce instantaneous velocity matching at top-dead-centre would be 66.89 mm. By increasing the radius of the crank to 68.26 mm and thereby its circumference to 428.95mm, which is an increase of approximately 2 percent, the speed of the carriage and hence the linear speed of the knives, at top-dead-centre, will be greater than that of the pallets. FIG. 2 shows the varying positions of the carriage relative to the varying positions of the pallet at 2 /2 degree intervals of motion of the crank member. The scale 67 represents the carriage and the scale 68 represents the pallets on the conveyor. It will be observed that for an interval of about one inch on either side of top-dead-centre there is no significant dif-- ference between the positions, certainly not enough difference to cause spoilage of the tiles.

In operation of the apparatus, pallets 12 are fed in a head to tail stream from conveyor 18 onto the links 15 and are carried under the concrete depositing apparatus 13 from which they emerge carrying a continuous ribbon 8 of contoured concrete having the transverse cross-section of a finished roofing tile. They then travel under the knife unit 14, which is synchronised with the conveyor such that, as the crank member 45 approaches the top-dead-centre position, so the joint between two pallets is correctly positioned for cutting. As each pallet moves forwardly to the cutting station, the cutting knife 23 is operated to sever the ribbon at the joint between two pallets, as described above, while simultaneously, at the trimming station, the trimming knife assembly, which is spaced ahead of the cutting knife assembly by slightly less than the length of two pallets, trims the leading edge of the next tile 9 in front of the tile being severed from the ribbon by the cutting knife. This trimming cut consists of the removal of a short length off the leading edge of each tile so that adjacent tiles 10 do not stick together during a subsequent curing process. As described above, the trimming knife is inclined to the tiles, and this results in the front edges of the tiles having a more pleasing appearance when laid on a roof. However, this is not essential and the trimming knife could be arranged normal to the tiles in like manner to the cutting knife. In order to ensure that the material removed the trimming knife does not lodge on the next tile ahead, the take away conveyor 19 is driven at a speed greater than that of the main conveyor 11, as mentioned above, so that the trimmed material falls in front of the tile from which it is removed and through a gap in the conveyor 19.

We claim:

1. Apparatus for cutting a continuously moving ribbon of tile forming material into discrete tiles of equal length and subsequently trimming the leading edge of each tile, comprising means for moving the ribbon past a cutting station at which the ribbon is cut into individual tiles and then past a trimming station at which the leading edge of each tile is trimmed, there being provided at at least one of said stations a knife holder mounted for reciprocal movement longitudinally of the direction of travel of the ribbon or tiles, means to effect said reciprocal movement of the holder, a knife mounted on the holder, and means to move the knife relative to the holder to perform its cutting action, said means for reciprocating the holder including a crank member, characterised in that the crank member is adapted to be rotated once for each length of tile that passes said one station and the throw of the crank member is selected so that during the cutting action of the knife the forward linear speed of the knife is first less than, then greater than, and then finally less than the speed of the ribbon or tile being cut. i

2. Apparatus according to claim 1, wherein the circumference of the circle described by the crank member is between 1 percent and 3 percent greater than each said tile length.

3. Apparatus according to claim 2, wherein said circumference is approximately 2 percent greater than each said tile length.

4. Apparatus according to claim 1, wherein the crank member is linked to the knife holder by a connecting rod, the axis of reciprocation of that end of the connecting rod attached to the holder being tangential to the circle of motion of the crank member.

5. Apparatus according to claim 1, wherein the knife is operated by a pneumatic cylinder.

6. Apparatus according to claim 1, including two said knives, one at said cutting station and the other at said trimming station.

7. Apparatus according to claim 6, wherein the knives are mounted on a single holder.

8. Apparatus according to claim 6, wherein the knives are spaced apart slightly less than an integral number of divided tile lengths, the lengths remaining in abutting relationship with one another after being cut by said one knife at the cutting station.

9. Apparatus according to claim 1, including a first conveyor for moving the ribbon to be cut to the cutting tile. 

1. Apparatus for cutting a continuously moving ribbon of tile forming material into discrete tiles of equal length and subsequently trimming the leading edge of each tile, comprising means for moving the ribbon past a cutting station at which the ribbon is cut into individual tiles and then past a trimming station at which the leading edge of each tile is trimmed, there being provided at at least one of said stations a knife holder mounted for reciprocal movement longitudinally of the direction of travel of the ribbon or tiles, means to effect said reciprocal movement of the holder, a knife mounted on the holder, and means to move the knife relative to the holder to perform its cutting action, said means for reciprocating the holder including a crank member, characterised in that the crank member is adapted to be rotated once for each length of tile that passes said one station and the throw of the crank member is selected so that during the cutting action of the knife the forward linear speed of the knife is first less than, then greater than, and then finally less than the speed of the ribbon or tile being cut.
 2. Apparatus according to claim 1, wherein the circumference Of the circle described by the crank member is between 1 percent and 3 percent greater than each said tile length.
 3. Apparatus according to claim 2, wherein said circumference is approximately 2 percent greater than each said tile length.
 4. Apparatus according to claim 1, wherein the crank member is linked to the knife holder by a connecting rod, the axis of reciprocation of that end of the connecting rod attached to the holder being tangential to the circle of motion of the crank member.
 5. Apparatus according to claim 1, wherein the knife is operated by a pneumatic cylinder.
 6. Apparatus according to claim 1, including two said knives, one at said cutting station and the other at said trimming station.
 7. Apparatus according to claim 6, wherein the knives are mounted on a single holder.
 8. Apparatus according to claim 6, wherein the knives are spaced apart slightly less than an integral number of divided tile lengths, the lengths remaining in abutting relationship with one another after being cut by said one knife at the cutting station.
 9. Apparatus according to claim 1, including a first conveyor for moving the ribbon to be cut to the cutting station and the tiles to be trimmed to the trimming station, and a second conveyor for removing the individual tiles from the trimming station, the speed of the second conveyor being greater than that of the first conveyor so that the material removed from each tile when it is trimmed does not lodge on the preceding tile.
 10. Apparatus according to claim 1, including a trimming knife at said trimming station, which knife is inclined to the ribbon to chamfer the front edge of each tile. 